Pi-minus he-4 inelastic and capture reactions leading to excited and multineutron final states

1968
9 pages
Published in:
  • Phys.Rev. 175 (1968) 1358-1366

Citations per year

197019811992200320143102
Abstract: (APS)
A beam of (140±0.5)-MeV π− was produced at the Berkely 184-in. cyclotron and used to study the finalstate interactions of three and four neutrons, and to look for excited levels of the α particle through the reactions {π−+He4,→π−+He*4,}{→p+3n,}{→d+2n,}{→π++4n.} Only one such level is found, with an excitation energy of 32 MeV and an intrinsic width smaller than our 1-MeV resolution. We find that our data on the four-neutron final state, although not inconsistent with phase space, agree more closely with the assumption that there is a S01 final-state interaction between two of the neutrons, the other two not interacting. We find, too, that deuteron production is down by a factor of ≈103 from proton production, and that the proton spectrum indicates a stronger-than-expected interaction between the three neutrons in the final state. Lower limits for the production of a tri- or tetraneutron are set.
  • pion minus-helium: interaction
  • interaction: pion minus-helium
  • final states 3
  • p: 3 neutrons
  • deuterium: 2 neutrons
  • pion plus: 4 neutrons
  • final state
  • plus: final state
  • final state: plus
  • capture